Balances of this type are known e.g. from Swiss patent 668,125. The use of separate data lines and an interface transducer outside of the explosive area in order to transmit data to and from the balance is also known (see e.g. D. Klausgrete: Elektronische Wagetechnik in explosiongefahrdeten Bereichen German=Electronic Weighing Technology in Explosive Areas!. Company publication of Sartorius AG (1991), pp. 43-46). General reference is also made to such US technical concepts set forth in the US Standards of the NFPA, "Standards for Intrinsically Safe Apparatus and Associated Apparatus for Use in Class I, II, and III, Division 1 Hazardous Locations," Copyright .COPYRGT. 1979 NFPA (National Fire Protection Association, 1 Batterymarch Park, Quincy, Mass. 02269-9101; &lt;webmaster@nfpa.org&gt;).
These known solutions have the disadvantages that the installation cost is relatively high on account of the separate cables for the voltage supply and for the data transmission and that the plurality of the required data lines renders a correspondingly thick and awkward cable with multipole plugs necessary. This high installation cost is especially disadvantageous for explosive areas with their special requirements.